Numerous manufacturing or processing operations involve the storage, supply and transfer of planar articles from one location to another. For example, sleeve-type carriers used to package beverage containers typically are formed from paperboard blanks which have been folded into collapsed, substantially flat form. A group or quantity of such folded paperboard carriers are consecutively arranged or loaded into a supply magazine, which delivers the carriers to an article transfer device. The article transfer device removes one carrier at a time from the supply magazine, and transfers the carrier to the desired location for further processing. The apparatus and method typically used in such operations are disclosed in U.S. Pat. No. 5,105,931, and in other of the U.S. Patents referred to therein. Another example of the supply and transfer of substantially planar articles in a manufacturing process also concerns the packaging of beverage containers, and specifically relates to supplying divider boards, such as paperboard separator sheets, in a packaging operation in which groups of stacked beverage containers are packaged in a sleeve-type carrier. U.S. Pat. No. 5,246,113 discloses various types of dividers or separator sheets and paperboard carriers.
A common requirement in the processing of both folded cartons and substantially planar divider sheets in such a packaging operation is that the cartons and divider sheets be continuously supplied during high-speed packaging processing, so that a single carton or sheet can be transferred from a supply area to a processing area. In order to accomplish such high-speed material transfer in packaging operations, large groups of cartons and dividers, for example, hundreds or even thousands in number, are arranged consecutively in a supply magazine which gravity feeds the articles to an article transfer device, such as the rotary multi-engagement device disclosed in U.S. Pat. No. 5,105,931. Some supply magazines include a powered mechanism to selectively feed the articles to the article transfer device. The present invention works effectively with either gravity fed or powered magazines. Such transfer devices are commonly known, and typically utilize vacuum engagement between the transfer device and the outermost or exposed article surface to remove the single article from the supply magazine, and then transfer the article to another location for further processing.
Typically, the grouped cartons or divider sheets are held in the supply magazine by upwardly and/or downwardly depending retaining bars. The bars are selectively disposed over the upper and lower side edges of the article sufficiently to releasably retain the article in the magazine, while allowing the vacuum engagement by the rotary transfer device to selectively remove an article or articles from engagement with the retaining bars. It is intended that only a single article be removed from the supply magazine by each vacuum engagement member. This specific process step, that is, selectively removing only one carton or divider sheet at a time from the supply magazine, can be very problematical. If the retaining bars of the magazine or hopper do not sufficiently overlap the edges of the article, the article group will not be retained in the hopper. Conversely, if the retaining bars overlap too great an extent, the article can be restrained from being easily picked by the vacuum transfer device. Trial and error adjustment of both the amount of such engagement and the force of the vacuum applied by the rotary transfer device usually are necessary to accomplish smooth operation in this process step. Even with the ability to adjust these process variables, however, it is often very difficult to cause this process to operate continuously at very high speeds while maintaining a high degree of efficiency.
Another problem associated with supplying a substantially flat, planar article in a high speed, continuous manufacturing operation, such as beverage container packaging, is that a vacuum effect tends to be created between successive articles in the hopper, causing more than one article to be pulled frown the hopper by the transfer device due to the tendency of the second article to temporarily adhere to the first or selected article. This is very undesirable, because the entire high speed operation can be interrupted if more than one article is selected, thereby causing an extreme loss of efficiency in the operation. This adherence between articles is the result of the articles necessarily being consecutively stacked, or arranged in large groups within the hopper which extends at a downward angle toward the rotary transfer device in order to allow the articles to be gravity fed. Consequently, there is little or no space between the articles, which creates a vacuum effect. That is, when the outermost article is pulled from the article group, one or more additional articles tend to be momentarily attracted to or held to the outermost article, causing one or more additional articles to be pulled from the hopper. This problem is not restricted to packaging operations in which substantially planar cartons or divider sheets are supplied in a continuous packaging operation. Many other high speed, automated processes which handle substantially planar articles also utilize gravity feed supply hoppers and article selection devices to select a single article from the hopper, and transfer the single article for further processing during the high-speed operation. These include practically all types of material packing operations which involve the handling of planar articles, including such operations which insert coupons, postcards or other planar articles or sheets into a packaged product, magazine, or envelope.
Although advances in the processing or packaging of articles have resulted in more efficient, more productive and higher speed article processing, the delivery of substantially planar articles in a manner which ensures singular article selection has remained a problem area in the process or operation.